The earliest reference in the patent literature to the hydraulic entanglement of fibrous sheet materials appears in patents issued to Bunting. In U.S. Pat. No. 3,560,326, Australian Patent No. 287,821 and Canadian Patent No. 739,652, Bunting describes a method for hydraulically treating sheet material using jet strips that are low gauge and uniformly arranged in a continuum and in a vertical orientation to the warp direction of the cloth.
This process represented, at the time, an improvement in the production of non-woven fabric; however, it employed columnar streams that were arranged solely in a single jet row.
Contractor, in U.S. Pat. No. 4,069,563, improved on U.S. Pat. No. 3,560,326 (Bunting) by substituting a staggered array of several jet rows for the single jet row which is there described. The non-woven fabric obtained by this process exhibited increased tensile strength; however, the degree of improvement was only on the order of about ten percent.
The first know reference to the hydraulic entanglement of woven and knit structures was also made by Bunting in Australian Patent 287,821 and Canadian Patent 739,652; however it has since been found that Bunting's use of columnar streams in low gauge and uniformly arranged jet strips in a vertical orientation to the warp direction results in streaking.
To prevent streaking and produce a more random and homogeneous appearance, Bunting positioned the jet streams at a biased angle in relation to the fabric support surface (FIG. 2 and FIG. 16B). When the support is a flat conveyor, the manifold could also be set at an angle which is oblique to the linear direction of the cloth (FIGS. 1 and 15) to produce minutely different impact angles and increase the ratio of jets to thread ends. While this arrangement can be achieved on a conveyor-like flat surface, it has no application in systems where the conveying surface is a roll. Aligning a roll on a bias with respect to the travel of the fabric causes the fabric to deviate from its machine direction path, and this makes tension control and tracking impossible. Moreover, the positioning of the manifold on a bias with respect to the roll makes the gap between each jet and the fabric surface non-equal. For this reason, although Bunting achieved some improvement in the physical and esthetic properties of fabrics treated on a flat surface, it had no practical application when the fabric being treated is supported on a foraminous and/or vacuum roll and the manifold is at an oblique angle.
It was not until Sternlieb, in U.S. Pat. No. 4,967,456, directed a "continuous curtain" of water onto a fabric surface that a practical method for hydro-enhancing fabric was realized.
In Sternlieb, the curtain of water is achieved by utilizing a jet strip 1 (FIG. 4C) having a single row of sixty jets per inch at a jet diameter of 0.005 inches. The jets are perpendicular to the fabric surface and they are arrayed in a manifold that is oriented at a right angle with respect to the direction of travel of the fabric. A vacuum is employed beneath each jet array to assist in the removal of excess water. To achieve the desired enhancement, at least 0.1 horsepower per pound (HP-Hr/Lb) of energy is expended. The means by which energy consumption is calculated, is described in detail in U.S. Pat. No. 3,449,809.
Unfortunately, neither the Bunting or Sternlieb method offers a practical solution to the hydraulic entanglement problem. Sternlieb employs high-density, single row jet strips 1 (FIG. 4C and FIG. 15) which are perpendicular to the fabric surface and, at right angles, to the machine direction of fabric transport (FIGS. 4A and 4B.) This method, using jet strips with 60 holes per inch, has a tendency to produce jet streaks when the holes per inch of the jet strip are less than the number of warp ends per inch in the fabric being processed. Moreover, the number of holes that can be inscribed into a single row jet strip are limited in the Sternlieb method. This limits the number of warp ends that can be processed.
Also, Bunting and Sternlieb describe their mechanisms as single pass operations, that is, the fabric passes under a plurality of manifolds only once. In these systems, the fabric enters at one end and exits at the opposite end as a finished textile.
Also, Bunting and Sternlieb show hydraulic enhancement occurring over a flat surface with a conveying wire serving as a means for transporting the fabric over a vacuum. In the Bunting method, there is no apparatus that employs any other surface.
Accordingly, there is a need for an improved textile hydroenhancing process and apparatus (i.e., system) for producing a variety of novel woven and knit fabrics which exhibit enhanced surface finish, cover, abrasion resistance, drape, reduced air permeability, wrinkle recovery and resistance to edge fray, in a manner which is inexpensive and efficient.
In this specification, reference is made to various terms and, also, the properties of the fabrics which are to be treated and produced; these terms and properties include, for example, "fibrous sheet material"; "yarn count"; "thread count"; and the like.
By "fibrous sheet material" is meant any natural or synthetically occurring sheet-like fabric which is comprised of staple fibers, continuous filaments, yarns or webs, whether they be woven, knitted, or non-woven. Also included are layered composites.
"Yarn count" refers to yarn size, and it defines the relationship between fiber yarn length and weight.
"Thread count" defines the number of ends, picks, wales or courses per inch of a fabric. The count is indicated by enumerating first the number of warp ends per inch followed by the number of filling picks per inch. Accordingly, a fabric having 75 warp ends and 85 filling picks per inch would have a thread count of 75 by 85.
"Bias" or "biased angle" describes the angle formed by the jet(s) and the fabric surface at impact.
"Oblique" or "oblique angle" refers to the orientation of the jet's vane(s) or manifold(s) with respect to the direction of fabric travel.
"Diagonal" or "diagonal angle" is used herein in a general sense to describe an angle other than a "biased angle" or "oblique angle."